Development of new multiepitope DNA vaccines for active immunotherapy against neuroblastoma combined with immune checkpoint blockade

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Neuroblastoma (NB) is a still challenging cancer of childhood with poor prognosis. Recently, GD2-directed immunotherapies improved survival of high-risk NB patients by 15%. As with most passive immunotherapies, such a strategy does not induce a long-lasting immune response and repeated Ab applications are necessary. This obstacle can be avoided by DNA vaccination.In the present project, we aim to generate a new mutiepitope DNA vaccine against NB. We previously successfully generated a bicistronic IL-15-based DNA vaccine against the tumor-associated antigen (TAA) tyrosine hydroxylase (TH) overexpressed in NB. Evaluation of this vaccine in our syngeneic mouse model clearly showed increased antitumor efficacy by IL-15 compared to the IL-15-free control TH vaccine. Our expertise and new knowledge in the field of DNA vaccination will be used for the generation of a more effective new generation multiepitope DNA vaccine against NB. To increase immunogenicity, further NB-specific TAAs (ALK, MYCN, survivin) will be integrated into the vaccine additionally to TH. This allows antitumor effects even after loss of some TAAs by tumor cells. To induce long-lasting effects, additional activation of T helper cells stimulating antigen presenting cells (APCs) and thereby activating tumor-specific cytotoxic T cells (CTLs) will be performed. For that, DNA sequences encoding universal T helper cell epitopes will be integrated into the vaccine. Furthermore, for effective loading of TAA- and T helper epitopes onto MHC-I and –II molecules, respectively, both lysosomal and proteasomal antigen presentation pathways will be induced by the DNA vaccine-dependent synthesis of the mutated ubiquitin with increased stability (polyubiquitination). An additional stimulation of APCs will be achieved by the vaccine-mediated synthesis of IL-15. After generation and characterization, antitumor efficacy of the new DNA vaccine will be evaluated in our preclinical NB model. For that, a new non-viral liposome-based nanoparticle vaccination strategy will be utilized. To overcome a tumor-mediated inhibition of immune response, an additional blockade of two immune checkpoints (PD-L1 + TIGIT) that have been shown to play an important role in cancer will be performed.In summary, we aim to generate a new generation cytokine-based DNA vaccine against different NB-specific TAAs that will be tested in combination with immune checkpoint blockade for induction of a long-lasting immune response against NB.